/*
 * Copyright 2002-2006 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core;

/**
 * 那些可排序的对象可以实现这个接口，例如在一个集合中。<br/>
 * Interface that can be implemented by objects that should be orderable, for
 * example in a Collection.
 * 
 * <p>
 * The actual order can be interpreted as prioritization, with the first object
 * (with the lowest order value) having the highest priority.
 * 
 * @author Juergen Hoeller
 * @since 07.04.2003
 * @see OrderComparator
 * @see org.springframework.core.annotation.Order
 */
public interface Ordered {

	/**
	 * Useful constant for the highest precedence value.
	 * 
	 * @see java.lang.Integer#MIN_VALUE
	 */
	int HIGHEST_PRECEDENCE = Integer.MIN_VALUE;

	/**
	 * Useful constant for the lowest precedence value.
	 * 
	 * @see java.lang.Integer#MAX_VALUE
	 */
	int LOWEST_PRECEDENCE = Integer.MAX_VALUE;

	/**
	 * Return the order value of this object, with a higher value meaning
	 * greater in terms of sorting.
	 * <p>
	 * Normally starting with 0 or 1, with {@link #LOWEST_PRECEDENCE} indicating
	 * greatest. Same order values will result in arbitrary positions for the
	 * affected objects.
	 * <p>
	 * Higher value can be interpreted as lower priority, consequently the first
	 * object has highest priority (somewhat analogous to Servlet
	 * "load-on-startup" values).
	 * <p>
	 * Note that order values below 0 are reserved for framework purposes.
	 * Application-specified values should always be 0 or greater, with only
	 * framework components (internal or third-party) supposed to use lower
	 * values.
	 * 
	 * @return the order value
	 * @see #LOWEST_PRECEDENCE
	 */
	int getOrder();

}
